stevens



(No Model.) 2 S heets-Shee t 1.

' L. STEVENS.

. STEAM BOILER FURNACE.

No. 351,475. Patented 0ot."26, 1886.

2 Sheets-- Sheet 2.

(No Model.) 7

L. STEVENS.

STEAM BOILER FURNACE.

Patented Oct. '26, 1-886.

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N. PETERS Phclodjihogmphnr, Wnshinglnm ac.

UNITED STATES PATENT OF ICE.

LEVI STEVENS, OF- WASHINGTON, DISTRICT OF COLUMBIA.

STEAM-BOlLE R FURNACE.

SPECIFICATION forming part of Letters Patent No. 351,475, dated October 26, 1886.

A Application filed December 12, 1885. Serial No. 185,439. (h'o model.)

, ington city, in the District of Columbia, have invented a new and useful Improvement in Furnaces for Steam-Boilers; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, this specification.

My invention relates to improvements in the construction of furnaces for steamboilers, and has for its object to produce a perfect combusmaking a part of tion and consumption of the gases evolved from the burning fuel, and a consequent prevention of smoke and an economy in the gen eration of steam therewith.

In the accompanying drawings, Figure l is a longitudinal section taken centrally through my improved furnace, constructed under a tubular boiler, the boiler being shown 'inelevation; Fig. 2 is a transverse section in liner w,- and Figs. 3 and 4 are similar sections in the lines 3 y and z 2, respectively, of Fig. l.

A represents the tubular boiler of any approved form,supported in the customary manner by the walls A A, of the furnace for heating the same. B is the ash-pit, and B the fire-chamber of the furnace. B are its gratebars; D, the ash-pit door, andD the fire-door. The bridge-wall O, at the rear of the ash-pit and fire-box, is made-hollow, and is carried up far enough above the grate-bars to give proper depth to the fire-chamber B, and upon its top a superheater, G, of any approved construction, is fitted and connected with the boiler. This superheater is also connected by one or more pipes, H'H, with a transverse perforated pipe, I, fitted under the grate-bars, so thata supply of superheated steam is emitted therefrom in fine jets into the ash-pit B, to be carried up between the grate-bars B and through the bed of incandescent fuel thereon. Within this hollow bridge-wall O a hot-air chamber, E, is formed, and it is made to communicate by a series of apertures, F F1, pierced in opposite directions. through the inclosing-walls 0, near the top thereof, both with the firechamber B on one side, and with a combustion-chamber, M, on the opposite-side thereof. The hot-air chamber E is supplied with air by posed between the rear means of an opening communicating therewith from the ash-pit and controlled by a damper, D

The combustion-chamber M is inclosed between the bridge-wall 0, back of the fire-chamber and a second wall, -L, built transversely under the boiler, and whose upper portion alone is pierced with a series of small apertures, L L. (See Fig. 4.) A hanging wall or deflecting-arch, K K, (see Fig. 3,) is interwall, L, of the combustion-chamber and the hollow bridge-wall O of the fire-chamber, the top of the open arch K being about on a level with the top of the wall 0. The effect of this arch is to check the hot currents of combustible gases sweeping over the top of the wall 0 and divert and deflect them downward toward the lower solid portion of the rear wall, L, and thereby form countless eddies and counter-currents Within the combustion-chamber before reaching the series of small upper discharge-apertures, L L.

In the operation of my improved 'furnace the combustible properties of the gases escaping unconsumed from the bed of incandescent fuel upon the grate-bars in the firechamberB areincreased,and they are rendered more ready for oxidation by the discharge of a small-supply of highly superheated steam beneath the grate-bars at the point where the fuel is always in its most perfect state of 00111: bustion. This small amount of steam is readily decomposed in passing up through the incandescent fuel, and the hydrogen and carbonic-oxide gas formed by its decomposition commingle with the unconsumed gases escaping from the fuel before they pass up over the bridge-wall, and by combining therewith increase the percentage of their combustible properties. In this condition, and at the moment they pass in an intensely-heated and highly inflammable condition over the bridgewall 0, they are supplied with oxygen by means of the minute currents of hot air admitted thereto from the hot-air chamber E first through the aperturesF and then through the apertures F in the top of the wall, which said currents serve lJO'iDdllCG and intensify their combustion. The jets of pure hot air which issue from the apertures FF are brought more or less into opposition to said currents of hot unconsumed gases as they are deflected by the arch or hanging wall K, and, becoming thoroughly admixed therewith in the whirls and eddies which are created within the combustion-chamber M. by reason of the peculiar combination and arrangement of said hanging wall K K,with reference to the top of the bridge- ..wall 0, and to the series of cellular dischargeopenings L L in the upper portion of the rear wall, L, of said combustion-chamber, induce a complete combustion of said gases. By this ignition and complete combustion of the inflammable gases within the combustion-chamher they are made to develop and impart an increased percentage of heat to the boiler above said chamber, as well as in passing forward thence through the boiler-flues, while no unconsumed 'particles Whatever will remain to be discharged in the form of smoke.

My invention differs from that described in' Letters Patent to H. M. Brady, No. 294,007, of February 28, 1884, in that in Bradys furnace no superheater is employed. The steam and air are delivered at a comparatively low temperature to the gases after they have parted with much of their caloric and are measurably cooled, and the second orrear bridgewall of the combustion-chamber is provided with a large full discharge-opening, whereas in my invention the steam is highly superheated and then delivered under the incan= descent bed of coals in the fire-chamber, so that the heatunits absorbed in its decomposition are quickly returned to the furnace. Highly-heated air is supplied through the bridge-wall immediately at the rear of the fire-chamber to the admixed gases from the fuel and steam when they are at the hottest,

and in such manner, by reason of the arrangement of the hanging Wall in combination with the series of sinallapertures in the upper part of the rear wall of the eombustion-chamber, as not to reduce their temperature, but by a quick complete admixture therewith promote an immediate ignition and combustion thereof. It differs from the invention described in the patent to P. \V. Frain, No. 285,887, October 2, 1883, in that in Frains furnace no provision is made for increasing the combustible properties of the gases escaping from the fuel by means of superheated steam,while the supply of air is admitted at a comparatively low temperature to the second or combustion chamber beyond a deflecting-arch therein at a point where the escaping gases have already become measurably cooled. I In its construction also the second or combustion chamber 'is so shallow as that it does not perform the function of creating eddies and counter-currents, which in my device are of great importance in connection with the admission of hot air, as specified. Moreover the outlet from said chamber is not broken up into aseries of small apertures.

I do not herein claim the construction of the bridge-wall O with its inclosed hot-air chamber E, nor the combination therewith of the superheater-G, nor, broadly, the arrangement of a combustion'ehamber at the rear of the fire-chamber, nor the combination of a deflecting arch or hanging wall with said chamber and the bridge-wall.

What I claim as my invention is r The combination, in a furnace, of the firechainber and ash-pit, the hollow bridge-wall back of the same, the combustion chamber formed in the rear .of the bridge-wall by a transverse rear wall pierced with a series of eduction-flues in its upper portion, the hang ing wall or deflecting arch interposed between the bridge-wall and rear wall, the air-chamber formed within the hollow bridge-wall and provided with an induction-opening communicating with the ash-pit, and eduction-ports communicating with the fire-chamber and combustion-chamber near the top-of the bridgewall, means for controlling the supply of air to the hot-air chamber, and a superheater within the furnace, communicating by dischargepipes with the ash-pit, all substantially in the manner and for the purpose here.- in set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

LEVI STEVENS.

\Vitnesses:

B. L. ARBEOAM, H. G. MoRsE. 

